In a cellular network with relay stations, such as, e.g., a cellular network implementing 802.16J, a popular implementation is to structure time division multiplexing between different types of traffic. For example, the downlink slots are divided into three types: base station to relay station, relay station to mobile station, and base station to mobile station, and a single logical sequence of downlink slots is followed throughout the cells of the network.
This approach of using a common slot allocation method throughout the system, is problematic from an interference perspective, particularly in boundary areas. For example, when two neighboring cells are transmitting data concurrently from their relay stations to mobile stations, mobile stations in cell boundary regions can be expected to suffer from inter-cell interference and may suffer from a bad signal to interference noise ratio (SINR).
Based on the above discussion, there is a need for new methods and apparatus to mitigate interference in wireless communications systems which use relay stations.